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<tr class="t-nv"><td colspan="5"> <a href="implicit_cast.html" title="cpp/language/implicit conversion"> Implicit conversions</a> - <a href="explicit_cast.html" title="cpp/language/explicit cast"> Explicit conversions</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="static_cast.html" title="cpp/language/static cast"><tt>static_cast</tt></a> - <a href="dynamic_cast.html" title="cpp/language/dynamic cast"><tt>dynamic_cast</tt></a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="const_cast.html" title="cpp/language/const cast"><tt>const_cast</tt></a> - <a href="reinterpret_cast.html" title="cpp/language/reinterpret cast"><tt>reinterpret_cast</tt></a></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Memory allocation</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="new.html" title="cpp/language/new"> <code>new</code> expression</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="delete.html" title="cpp/language/delete"> <code>delete</code> expression</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> <a href="classes.html" title="cpp/language/classes"> Classes</a></td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="class.html" title="cpp/language/class"> Class declaration</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="initializer_list.html" title="cpp/language/constructor"> Constructors</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="this.html" title="cpp/language/this"> <code>this</code> pointer</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="access.html" title="cpp/language/access"> Access specifiers</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="friend.html" title="cpp/language/friend"> <code>friend</code> specifier</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Class-specific function properties</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="virtual.html" title="cpp/language/virtual"> Virtual function</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="override.html" title="cpp/language/override"> <code>override</code> specifier</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="final.html" title="cpp/language/final"> <code>final</code> specifier</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="explicit.html" title="cpp/language/explicit"><tt>explicit</tt></a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="static.html" title="cpp/language/static"><tt>static</tt></a> </td></tr>
</table></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Special member functions</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="default_constructor.html" title="cpp/language/default constructor"> Default constructor</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="copy_constructor.html" title="cpp/language/copy constructor"> Copy constructor</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="move_constructor.html" title="cpp/language/move constructor"> Move constructor</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="as_operator.html" title="cpp/language/as operator" class="mw-redirect"> Copy assignment</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="move_operator.html" title="cpp/language/move operator" class="mw-redirect"> Move assignment</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="destructor.html" title="cpp/language/destructor"> Destructor</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"><a href="templates.html" title="cpp/language/templates"> Templates</a> </td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="class_template.html" title="cpp/language/class template"> Class template </a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="function_template.html" title="cpp/language/function template"> Function template </a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="template_specialization.html" title="cpp/language/template specialization"> Template specialization</a></td></tr>   
<tr class="t-nv"><td colspan="5"> <a href="parameter_pack.html" title="cpp/language/parameter pack"> Parameter packs</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> Miscellaneous </td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="asm.html" title="cpp/language/asm"> Inline assembly</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="history.html" title="cpp/language/history"> History of C++</a></td></tr>
</table></div></td></tr>
</table></div>
</div><div></div></div></div></div><div class="t-navbar-sep"> </div><div class="t-navbar-head"><strong class="selflink"> Declarations</strong><div class="t-navbar-menu"><div><div style="display:inline-block">
<div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv-h2"><td colspan="5"> Overview </td></tr>
<tr class="t-nv"><td colspan="5"> <strong class="selflink"> declaration syntax</strong> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="declarations.html#Specifiers" title="cpp/language/declarations"> decl-specifier-seq</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="declarations.html#Declarators" title="cpp/language/declarations"> declarator</a> </td></tr>
<tr class="t-nv-h2"><td colspan="5"> Specifiers </td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="typedef.html" title="cpp/language/typedef"><span class="t-lines"><span>typedef</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="inline.html" title="cpp/language/inline"><span class="t-lines"><span>inline</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="virtual.html" title="cpp/language/virtual"> <code>virtual</code> function specifier</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="explicit.html" title="cpp/language/explicit"> <code>explicit</code> function specifier</a>   </td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="friend.html" title="cpp/language/friend"><span class="t-lines"><span>friend</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="constexpr.html" title="cpp/language/constexpr"><span class="t-lines"><span>constexpr</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="consteval.html" title="cpp/language/consteval"><span class="t-lines"><span>consteval</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="constinit.html" title="cpp/language/constinit"><span class="t-lines"><span>constinit</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="storage_duration.html" title="cpp/language/storage duration"> storage class specifiers</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="tu_local.html" title="cpp/language/tu local"> translation-unit-local</a> <span class="t-mark-rev t-since-cxx20">(C++20)</span></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="class.html" title="cpp/language/class"><span class="t-lines"><span>class/struct</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="union.html" title="cpp/language/union"><span class="t-lines"><span>union</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="enum_class.html" title="cpp/language/enum"><span class="t-lines"><span>enum</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="decltype.html" title="cpp/language/decltype"><span class="t-lines"><span>decltype</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="auto.html" title="cpp/language/auto"><span class="t-lines"><span>auto</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="alignas.html" title="cpp/language/alignas"><span class="t-lines"><span>alignas</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="cv.html" title="cpp/language/cv"><span class="t-lines"><span>const</span><span>volatile</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="elaborated_type_specifier.html" title="cpp/language/elaborated type specifier"> elaborated type specifier</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="attributes.html" title="cpp/language/attributes"> attributes </a><span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv-h2"><td colspan="5"> Declarators </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="reference.html" title="cpp/language/reference"> reference </a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="pointer.html" title="cpp/language/pointer"> pointer </a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="array.html" title="cpp/language/array"> array </a> </td></tr>
<tr class="t-nv-h2"><td colspan="5"> Block declarations </td></tr>
<tr class="t-nv"><td colspan="5"> <strong class="selflink"> simple-declaration</strong> </td></tr>
<tr class="t-nv"><td colspan="5"> →<a href="structured_binding.html" title="cpp/language/structured binding"> structured binding declaration</a> <span class="t-mark-rev t-since-cxx17">(C++17)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="type_alias.html" title="cpp/language/type alias"> <code>alias</code> declaration</a><span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="namespace_alias.html" title="cpp/language/namespace alias"> namespace alias definition </a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="using_declaration.html" title="cpp/language/using declaration"> using-declaration</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="namespace.html#Using-directives" title="cpp/language/namespace"> using-directive</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="static_assert.html" title="cpp/language/static assert"> <code>static_assert</code> declaration</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="asm.html" title="cpp/language/asm"> asm-declaration</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="enum_class.html" title="cpp/language/enum"> opaque enum declaration</a><span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv-h2"><td colspan="5"> Other declarations </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="namespace.html" title="cpp/language/namespace"> namespace definition</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="function.html" title="cpp/language/function"> function declaration</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="class_template.html" title="cpp/language/class template"> class template declaration</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="function_template.html" title="cpp/language/function template"> function template declaration</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="class_template.html#Explicit_instantiation" title="cpp/language/class template"> explicit template instantiation</a><span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="template_specialization.html" title="cpp/language/template specialization"> explicit template specialization</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="language_linkage.html" title="cpp/language/language linkage"> linkage specification</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <strong class="selflink"> attribute declaration</strong> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <strong class="selflink"> empty declaration</strong> </td></tr>
</table></div></td></tr>
</table></div>
</div><div></div></div></div></div><div class="t-navbar-sep"> </div></div>
<p><i>Declarations</i> introduce (or re-introduce) names into the C++ program. Each kind of entity is declared differently. <a href="definition.html" title="cpp/language/definition">Definitions</a> are declarations that are sufficient to use the entity identified by the name. 
</p><p>A declaration is one of the following:
</p>
<ul><li> <a href="function.html#Function_definition" title="cpp/language/function">Function definition</a>
</li><li> <a href="templates.html" title="cpp/language/templates">Template declaration</a> (including <a href="partial_specialization.html" title="cpp/language/partial specialization">Partial template specialization</a>)
</li><li> <a href="class_template.html#Explicit_instantiation" title="cpp/language/class template">Explicit template instantiation</a>
</li><li> <a href="template_specialization.html" title="cpp/language/template specialization">Explicit template specialization</a>
</li><li> <a href="namespace.html" title="cpp/language/namespace">Namespace definition</a>
</li><li> <a href="language_linkage.html" title="cpp/language/language linkage">Linkage specification</a>
</li></ul>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<ul><li> Attribute declaration (<span class="t-spar"><a href="attributes.html" title="cpp/language/attributes">attr</a></span> <code><b>;</b></code>)
</li></ul>
</td>
<td><span class="t-mark-rev t-since-cxx11">(since C++11)</span></td></tr>
</table>
<ul><li> Empty declaration (<code><b>;</b></code>)
</li><li> A function declaration without a <span class="t-spar">decl-specifier-seq</span>:
</li></ul>
<table class="t-sdsc-begin">
<table class="t-sdsc-begin">

<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td class="t-sdsc-nopad"> <span class="t-spar">attr</span><span class="t-mark">(optional)</span> <span class="t-spar">declarator</span> <code><b>;</b></code>
</td>
<td class="t-sdsc-nopad">
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr></table>
<table class="t-par-begin">


<tr class="t-par">
<td> <span class="t-spar">attr</span>
</td>
<td> -
</td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span> sequence of any number of <a href="attributes.html" title="cpp/language/attributes">attributes</a>
</td></tr>
<tr class="t-par">
<td> <span class="t-spar">declarator</span>
</td>
<td> -
</td>
<td> a function declarator
</td></tr></table>
<dl><dd> This declaration must declare a constructor, destructor, or user-defined type <a href="cast_operator.html" title="cpp/language/cast operator">conversion function</a>. It can only be used as part of a <a href="templates.html" title="cpp/language/templates">template declaration</a>, <a href="template_specialization.html" title="cpp/language/template specialization">explicit specialization</a>, or explicit instantiation.
</dd></dl>
<ul><li> <span class="t-spar">block-declaration</span> (a declaration that can appear inside a <a href="statements.html#Compound_statement" title="cpp/language/statements">block</a>), which, in turn, can be one of the following:
</li></ul>
<dl><dd><ul><li><a href="asm.html" title="cpp/language/asm">asm declaration</a>
</li></ul>
</dd></dl>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<dl><dd><ul><li><a href="type_alias.html" title="cpp/language/type alias">type alias declaration</a>
</li></ul>
</dd></dl>
</td>
<td><span class="t-mark-rev t-since-cxx11">(since C++11)</span></td></tr>
</table>
<dl><dd><ul><li><a href="namespace_alias.html" title="cpp/language/namespace alias">namespace alias definition</a>
</li><li><a href="using_declaration.html" title="cpp/language/using declaration">using-declaration</a>
</li><li><a href="namespace.html#Using-directives" title="cpp/language/namespace">using directive</a>
</li></ul>
</dd></dl>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx20"><td>
<dl><dd><ul><li><a href="enum_class.html#Using-enum-declaration" title="cpp/language/enum">using-enum-declaration</a>
</li></ul>
</dd></dl>
</td>
<td><span class="t-mark-rev t-since-cxx20">(since C++20)</span></td></tr>
</table>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<dl><dd><ul><li><a href="static_assert.html" title="cpp/language/static assert"><code>static_assert</code></a> declaration
</li><li><a href="enum_class.html" title="cpp/language/enum">opaque enum declaration</a>
</li></ul>
</dd></dl>
</td>
<td><span class="t-mark-rev t-since-cxx11">(since C++11)</span></td></tr>
</table>
<dl><dd><ul><li>simple declaration
</li></ul>
</dd></dl>
<h3><span class="mw-headline" id="Simple_declaration">Simple declaration</span></h3>
<p>A simple declaration is a statement that introduces, creates, and optionally initializes one or several identifiers, typically variables.
</p>
<table class="t-sdsc-begin">

<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <span class="t-spar">decl-specifier-seq</span> <span class="t-spar">init-declarator-list</span><span class="t-mark">(optional)</span> <code><b>;</b></code>
</td>
<td> (1)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <span class="t-spar">attr</span> <span class="t-spar">decl-specifier-seq</span> <span class="t-spar">init-declarator-list</span><code><b>;</b></code>
</td>
<td> (2)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr></table>
<table class="t-par-begin">


<tr class="t-par">
<td> <span class="t-spar">attr</span>
</td>
<td> -
</td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span> sequence of any number of <a href="attributes.html" title="cpp/language/attributes">attributes</a>
</td></tr>
<tr class="t-par">
<td> <span class="t-spar">decl-specifier-seq</span>
</td>
<td> -
</td>
<td> sequence of <i>specifiers</i> (see below)
</td></tr>
<tr class="t-par">
<td> <span class="t-spar">init-declarator-list</span>
</td>
<td> -
</td>
<td> comma-separated list of <i>declarators</i> with optional <i>initializers</i>. <span class="t-spar">init-declarator-list</span> is optional when declaring a named class/struct/union or a named enumeration
</td></tr></table>
<p><span class="t-rev-inl t-since-cxx17"><span>A <a href="structured_binding.html" title="cpp/language/structured binding">structured binding declaration</a> is also a simple declaration.</span> <span><span class="t-mark-rev t-since-cxx17">(since C++17)</span></span></span>
</p>
<h3><span class="mw-headline" id="Specifiers">Specifiers</span></h3>
<p><b>Declaration specifiers</b> (<span class="t-spar">decl-specifier-seq</span>) is a sequence of the following whitespace-separated specifiers, in any order:
</p>
<ul><li> the <a href="typedef.html" title="cpp/language/typedef"><code>typedef</code></a> specifier. If present, the entire declaration is a <a href="typedef.html" title="cpp/language/typedef">typedef declaration</a> and each declarator introduces a new type name, not an object or a function.
</li><li> function specifiers (<a href="inline.html" title="cpp/language/inline"><code>inline</code></a>, <a href="virtual.html" title="cpp/language/virtual"><code>virtual</code></a>, <a href="explicit.html" title="cpp/language/explicit"><code>explicit</code></a>), only allowed in <a href="function.html" title="cpp/language/function">function declarations</a>
</li></ul>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx17"><td>
<ul><li> the <a href="inline.html" title="cpp/language/inline"><code>inline</code></a> specifier is also allowed on variable declarations.
</li></ul>
</td>
<td><span class="t-mark-rev t-since-cxx17">(since C++17)</span></td></tr>
</table>
<ul><li> the <a href="friend.html" title="cpp/language/friend"><code>friend</code></a> specifier, allowed in class and function declarations.
</li></ul>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<ul><li> the <a href="constexpr.html" title="cpp/language/constexpr"><code>constexpr</code></a> specifier, only allowed in variable definitions, function and function template declarations, and the declaration of static data members of literal type.
</li></ul>
</td>
<td><span class="t-mark-rev t-since-cxx11">(since C++11)</span></td></tr>
</table>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx20"><td>
<ul><li> the <a href="consteval.html" title="cpp/language/consteval"><code>consteval</code></a> specifier, only allowed in function and function template declarations.
</li><li> the <a href="constinit.html" title="cpp/language/constinit"><code>constinit</code></a> specifier, only allowed in declaration of a variable with static or thread storage duration. At most one of the <code>constexpr</code>, <code>consteval</code>, and <code>constinit</code> specifiers is allowed to appear in a <span class="t-spar">decl-specifier-seq</span>.
</li></ul>
</td>
<td><span class="t-mark-rev t-since-cxx20">(since C++20)</span></td></tr>
</table>
<ul><li> <a href="storage_duration.html" title="cpp/language/storage duration">storage class specifier</a> (<span class="t-rev-inl t-until-cxx17"><span><a href="../keyword/register.html" title="cpp/keyword/register"><tt>register</tt></a>, </span> <span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span> <a href="../keywords/static.html" title="cpp/keyword/static"><tt>static</tt></a>, <span class="t-rev-inl t-since-cxx11"><span><a href="../keyword/thread_local.html" title="cpp/keyword/thread local"><tt>thread_local</tt></a>, </span> <span><span class="t-mark-rev t-since-cxx11">(since C++11)</span></span></span> <a href="../keyword/extern.html" title="cpp/keyword/extern"><tt>extern</tt></a>, <a href="../keyword/mutable.html" title="cpp/keyword/mutable"><tt>mutable</tt></a>). Only one storage class specifier is allowed, except that <code>thread_local</code> may appear together with <code>extern</code> or <code>static</code>.
</li><li> <b>Type specifiers</b> (<span class="t-spar">type-specifier-seq</span>), a sequence of specifiers that names a type. The type of every entity introduced by the declaration is this type, optionally modified by the declarator (see below). This sequence of specifiers is also used by <a href="type-id.html#Type_naming" title="cpp/language/type">type-id</a>. Only the following specifiers are part of <span class="t-spar">type-specifier-seq</span>, in any order:
</li></ul>
<dl><dd><ul><li> <a href="class.html" title="cpp/language/class">class specifier</a>
</li><li> <a href="enum_class.html" title="cpp/language/enum">enum specifier</a>
</li><li> simple type specifier
</li></ul>
<dl><dd><ul><li><a href="../keyword/char.html" title="cpp/keyword/char"><tt>char</tt></a>, <span class="t-rev-inl t-since-cxx20"><span><a href="../keyword/char8_t.html" title="cpp/keyword/char8 t"><tt>char8_t</tt></a>, </span> <span><span class="t-mark-rev t-since-cxx20">(since C++20)</span></span></span> <span class="t-rev-inl t-since-cxx11"><span><a href="../keyword/char16_t.html" title="cpp/keyword/char16 t"><tt>char16_t</tt></a>, <a href="../keyword/char32_t.html" title="cpp/keyword/char32 t"><tt>char32_t</tt></a>, </span> <span><span class="t-mark-rev t-since-cxx11">(since C++11)</span></span></span> <a href="../keyword/wchar_t.html" title="cpp/keyword/wchar t"><tt>wchar_t</tt></a>, <a href="../keyword/bool.html" title="cpp/keyword/bool"><tt>bool</tt></a>, <a href="../keyword/short.html" title="cpp/keyword/short"><tt>short</tt></a>, <a href="../keyword/int.html" title="cpp/keyword/int"><tt>int</tt></a>, <a href="../keyword/long.html" title="cpp/keyword/long"><tt>long</tt></a>, <a href="../keyword/signed.html" title="cpp/keyword/signed"><tt>signed</tt></a>, <a href="../keyword/unsigned.html" title="cpp/keyword/unsigned"><tt>unsigned</tt></a>, <a href="../keyword/float.html" title="cpp/keyword/float"><tt>float</tt></a>, <a href="../keyword/double.html" title="cpp/keyword/double"><tt>double</tt></a>, <a href="../keyword/void.html" title="cpp/keyword/void"><tt>void</tt></a>
</li></ul>
</dd></dl>
</dd></dl>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<dl><dd><dl><dd><ul><li><a href="auto.html" title="cpp/language/auto"><code>auto</code></a>
</li><li><a href="decltype.html" title="cpp/language/decltype">decltype specifier</a>
</li></ul>
</dd></dl>
</dd></dl>
</td>
<td><span class="t-mark-rev t-since-cxx11">(since C++11)</span></td></tr></table>
<dl><dd><dl><dd><ul><li> previously declared class name (optionally <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">qualified</a>)
</li><li> previously declared enum name (optionally <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">qualified</a>)
</li><li> previously declared <a href="typedef.html" title="cpp/language/typedef">typedef-name</a><span class="t-rev-inl t-since-cxx11"><span> or <a href="type_alias.html" title="cpp/language/type alias">type alias</a></span> <span><span class="t-mark-rev t-since-cxx11">(since C++11)</span></span></span> (optionally <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">qualified</a>)
</li><li> template name with template arguments (optionally <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">qualified</a>, optionally using <a href="dependent_name.html" title="cpp/language/dependent name">template disambiguator</a>)
</li></ul>
</dd></dl>
</dd></dl>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx17"><td>
<dl><dd><dl><dd><ul><li>template name without template arguments (optionally <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">qualified</a>): see <a href="deduction_guide.html" title="cpp/language/class template argument deduction">class template argument deduction</a>
</li></ul>
</dd></dl>
</dd></dl>
</td>
<td><span class="t-mark-rev t-since-cxx17">(since C++17)</span></td></tr></table>
<dl><dd><ul><li> <a href="elaborated_type_specifier.html" title="cpp/language/elaborated type specifier">elaborated type specifier</a>
</li></ul>
<dl><dd><ul><li> the keyword <a href="../keyword/class.html" title="cpp/keyword/class"><tt>class</tt></a>, <a href="../keyword/struct.html" title="cpp/keyword/struct"><tt>struct</tt></a>, or <a href="../keyword/union.html" title="cpp/keyword/union"><tt>union</tt></a>, followed by the identifier (optionally <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">qualified</a>), previously defined as the name of a class, struct, or union.
</li><li> the keyword <a href="../keyword/class.html" title="cpp/keyword/class"><tt>class</tt></a>, <a href="../keyword/struct.html" title="cpp/keyword/struct"><tt>struct</tt></a>, or <a href="../keyword/union.html" title="cpp/keyword/union"><tt>union</tt></a>, followed by template name with template arguments (optionally <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">qualified</a>, optionally using <a href="dependent_name.html" title="cpp/language/dependent name">template disambiguator</a>), previously defined as the name of a class template.
</li><li> the keyword <a href="../keyword/enum.html" title="cpp/keyword/enum"><tt>enum</tt></a> followed by the identifier (optionally <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">qualified</a>), previously declared as the name of an enumeration.
</li></ul>
</dd></dl>
<ul><li> <a href="dependent_name.html" title="cpp/language/dependent name">typename specifier</a>
</li><li> <a href="cv.html" title="cpp/language/cv">cv qualifier</a>
</li></ul>
</dd><dd>only one type specifier is allowed in a decl-specifier-seq, with the following exceptions:
<ul><li> <code>const</code> can be combined with any type specifier except itself.
</li><li> <code>volatile</code> can be combined with any type specifier except itself.
</li><li> <code>signed</code> or <code>unsigned</code> can be combined with <code>char</code>, <code>long</code>, <code>short</code>, or <code>int</code>.
</li><li> <code>short</code> or <code>long</code> can be combined with <code>int</code>.
</li><li> <code>long</code> can be combined with <code>double</code>.
</li></ul>
</dd></dl>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<dl><dd><ul><li> <code>long</code> can be combined with <code>long</code>.
</li></ul>
</dd></dl>
</td>
<td><span class="t-mark-rev t-since-cxx11">(since C++11)</span></td></tr>
</table>
<p><a href="attributes.html" title="cpp/language/attributes">Attributes</a> may appear in <span class="t-spar">decl-specifier-seq</span>, in which case they apply to the type determined by the preceding specifiers.
</p><p>Repetitions of any specifier in a <span class="t-spar">decl-specifier-seq</span>, such as <code>const static const</code>, or <code>virtual inline virtual</code> are errors<span class="t-rev-inl t-since-cxx11"><span>, except that <code>long</code> is allowed to appear twice</span> <span><span class="t-mark-rev t-since-cxx11">(since C++11)</span></span></span>.
</p>
<h3><span class="mw-headline" id="Declarators">Declarators</span></h3>
<p><span class="t-spar">init-declarator-list</span> is a comma-separated sequence of one or more <span class="t-spar">init-declarators</span>, which have the following syntax:
</p>
<table class="t-sdsc-begin">

<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <span class="t-spar">declarator</span> <span class="t-spar">initializer</span><span class="t-mark">(optional)</span>
</td>
<td> (1)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <span class="t-spar">declarator</span> <span class="t-spar">requires-clause</span>
</td>
<td> (2)
</td>
<td> <span class="t-mark-rev t-since-cxx20">(since C++20)</span>
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr></table>
<table class="t-par-begin">


<tr class="t-par">
<td> <span class="t-spar">declarator</span>
</td>
<td> -
</td>
<td> the declarator
</td></tr>
<tr class="t-par">
<td> <span class="t-spar">initializer</span>
</td>
<td> -
</td>
<td> optional initializer (except where required, such as when initializing references or const objects). See <a href="initialization.html" title="cpp/language/initialization">Initialization</a> for details.
</td></tr>
<tr class="t-par">
<td> <span class="t-spar">requires-clause</span>
</td>
<td> -
</td>
<td> <a href="constraints.html#Requires_clauses" title="cpp/language/constraints">a requires-clause</a>, which adds a <a href="constraints.html" title="cpp/language/constraints">constraint</a> to a <a href="function.html" title="cpp/language/function">function declaration</a>
</td></tr></table>
<p>Each <span class="t-spar">init-declarator</span> in a init-declarator sequence <span class="t-c"><span class="mw-geshi cpp source-cpp">S D1, D2, D3<span class="sy4">;</span></span></span> is processed as if it were a standalone declaration with the same specifiers: <span class="t-c"><span class="mw-geshi cpp source-cpp">S D1<span class="sy4">;</span> S D2<span class="sy4">;</span> S D3<span class="sy4">;</span></span></span>.
</p><p>Each declarator introduces exactly one object, reference, function, or (for typedef declarations) type alias, whose type is provided by <span class="t-spar">decl-specifier-seq</span> and optionally modified by operators such as <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">&amp;</span></span></span> (reference to) or <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">[</span><span class="br0">]</span></span></span> (array of) or <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span><span class="br0">)</span></span></span> (function returning) in the declarator. These operators can be applied recursively, as shown below.
</p><p>A <span class="t-spar">declarator</span> is one of the following:
</p>
<table class="t-sdsc-begin">

<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <span class="t-spar">unqualified-id</span> <span class="t-spar">attr</span><span class="t-mark">(optional)</span>
</td>
<td> (1)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <span class="t-spar">qualified-id</span> <span class="t-spar">attr</span><span class="t-mark">(optional)</span>
</td>
<td> (2)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <code><b>...</b></code> <span class="t-spar">identifier</span> <span class="t-spar">attr</span><span class="t-mark">(optional)</span>
</td>
<td> (3)
</td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span>
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <code><b>*</b></code> <span class="t-spar">attr</span><span class="t-mark">(optional)</span> <span class="t-spar">cv</span><span class="t-mark">(optional)</span> <span class="t-spar">declarator</span>
</td>
<td> (4)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <span class="t-spar">nested-name-specifier</span> <code><b>*</b></code> <span class="t-spar">attr</span><span class="t-mark">(optional)</span> <span class="t-spar">cv</span><span class="t-mark">(optional)</span> <span class="t-spar">declarator</span>
</td>
<td> (5)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <code><b>&amp;</b></code> <span class="t-spar">attr</span><span class="t-mark">(optional)</span> <span class="t-spar">declarator</span>
</td>
<td> (6)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <code><b>&amp;&amp;</b></code> <span class="t-spar">attr</span><span class="t-mark">(optional)</span> <span class="t-spar">declarator</span>
</td>
<td> (7)
</td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span>
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <span class="t-spar">noptr-declarator</span> <code><b>[</b></code> <span class="t-spar">constexpr</span><span class="t-mark">(optional)</span> <code><b>]</b></code> <span class="t-spar">attr</span><span class="t-mark">(optional)</span>
</td>
<td> (8)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td> <span class="t-spar">noptr-declarator</span> <code><b>(</b></code> <span class="t-spar">parameter-list</span> <code><b>)</b></code> <span class="t-spar">cv</span><span class="t-mark">(optional)</span> <span class="t-spar">ref</span><span class="t-mark">(optional)</span> <span class="t-spar">except</span><span class="t-mark">(optional)</span> <span class="t-spar">attr</span><span class="t-mark">(optional)</span>
</td>
<td> (9)
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr></table>
<div class="t-li1"><span class="t-li">1)</span> The <a href="name.html" title="cpp/language/name" class="mw-redirect">name</a> that is declared.</div>
<div class="t-li1"><span class="t-li">2)</span> A declarator that uses a <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">qualified identifier</a> (<span class="t-spar">qualified-id</span>) defines or redeclares a previously declared  <a href="namespace.html#Namespaces" title="cpp/language/namespace">namespace member</a> or <a href="classes.html" title="cpp/language/classes">class member</a>.</div>
<div class="t-li1"><span class="t-li">3)</span> <a href="parameter_pack.html" title="cpp/language/parameter pack">Parameter pack</a>, only appears in <a href="function.html#Parameter_list" title="cpp/language/function">parameter declarations</a>.</div>
<div class="t-li1"><span class="t-li">4)</span> <a href="pointer.html" title="cpp/language/pointer">Pointer declarator</a>: the declaration <span class="t-c"><span class="mw-geshi cpp source-cpp">S <span class="sy2">*</span> D<span class="sy4">;</span></span></span> declares <code>D</code> as a pointer to the type determined by <span class="t-spar">decl-specifier-seq</span> <code>S</code>.</div>
<div class="t-li1"><span class="t-li">5)</span> <a href="pointer.html" title="cpp/language/pointer">Pointer to member declaration</a>: the declaration <span class="t-c"><span class="mw-geshi cpp source-cpp">S C<span class="sy4">::</span><span class="sy2">*</span> D<span class="sy4">;</span></span></span> declares <code>D</code> as a pointer to member of <code>C</code> of type determined by <span class="t-spar">decl-specifier-seq</span> <code>S</code>. <span class="t-spar">nested-name-specifier</span> is a <a href="name.html#Qualified_identifiers" title="cpp/language/identifiers">sequence of names and scope resolution operators <code><b>::</b></code></a></div>
<div class="t-li1"><span class="t-li">6)</span> <a href="reference.html" title="cpp/language/reference">Lvalue reference declarator</a>: the declaration <span class="t-c"><span class="mw-geshi cpp source-cpp">S <span class="sy3">&amp;</span> D<span class="sy4">;</span></span></span> declares <code>D</code> as an lvalue reference to the type determined by <span class="t-spar">decl-specifier-seq</span> <code>S</code>.</div>
<div class="t-li1"><span class="t-li">7)</span> <a href="reference.html" title="cpp/language/reference">Rvalue reference declarator</a>: the declaration <span class="t-c"><span class="mw-geshi cpp source-cpp">S <span class="sy3">&amp;&amp;</span> D<span class="sy4">;</span></span></span> declares <code>D</code> as an rvalue reference to the type determined by <span class="t-spar">decl-specifier-seq</span> <code>S</code>.</div>
<div class="t-li1"><span class="t-li">8)</span> <a href="array.html" title="cpp/language/array">Array declarator</a>. <span class="t-spar">noptr-declarator</span> any valid declarator, but if it begins with *, &amp;, or &amp;&amp;, it has to be surrounded by parentheses.</div>
<div class="t-li1"><span class="t-li">9)</span> <a href="function.html" title="cpp/language/function">Function declarator</a>. <span class="t-spar">noptr-declarator</span> any valid declarator, but if it begins with *, &amp;, or &amp;&amp;, it has to be surrounded by parentheses. <span class="t-rev-inl t-since-cxx11"><span>Note that the outermost function declarator may end with the optional trailing return type.</span> <span><span class="t-mark-rev t-since-cxx11">(since C++11)</span></span></span></div>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<p>In all cases, <span class="t-spar">attr</span> is an optional sequence of <a href="attributes.html" title="cpp/language/attributes">attributes</a>. When appearing immediately after the identifier, it applies to the object being declared.
</p>
</td>
<td><span class="t-mark-rev t-since-cxx11">(since C++11)</span></td></tr>
</table>
<p><span class="t-spar">cv</span> is a sequence of <a href="cv.html" title="cpp/language/cv">const and volatile</a> qualifiers, where either qualifier may appear at most once in the sequence.
</p>
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style=""><tr><td class="mbox-empty-cell"></td><td class="mbox-text" style="">This section is incomplete<br>Reason: explain declaration name hiding rules; how a variable/function declaration hides a class (but not a typedef) with the same name </td></tr></table>
<h3><span class="mw-headline" id="Notes">Notes</span></h3>
<p>When a <span class="t-spar">block-declaration</span> appears <a href="statements.html#Compound_statements" title="cpp/language/statements">inside a block</a>, and an identifier introduced by a declaration was previously declared in an outer block, the <a href="scope.html" title="cpp/language/scope">outer declaration is hidden</a> for the remainder of the block. 
</p><p>If a declaration introduces a variable with automatic storage duration, it is initialized when its declaration statement is executed. All automatic variables declared in a block are destroyed on exit from the block (regardless how the block is exited: via <a href="exceptions.html" title="cpp/language/exceptions">exception</a>, <a href="goto.html" title="cpp/language/goto">goto</a>, or by reaching its end), in order opposite to their order of initialization.
</p>
<h3><span class="mw-headline" id="Examples">Examples</span></h3>
<div class="t-example"><p>Note: this example demonstrates how some complex declarations are parsed in terms of the language grammar. Other popular mnemonics are: <a rel="nofollow" class="external text" href="http://c-faq.com/decl/spiral.anderson.html">the spiral rule</a>, reading <a rel="nofollow" class="external text" href="https://stackoverflow.com/a/34560439/273767">inside-out</a>, and <a rel="nofollow" class="external text" href="https://stackoverflow.com/a/34552915/273767">declaration mirrors use</a>. There is also an automated parser at <a rel="nofollow" class="external free" href="http://cdecl.org">http://cdecl.org</a></p><div class="t-example-live-link"><div class="coliru-btn coliru-btn-run-init">Run this code</div></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="co2">#include &lt;string&gt;</span>
 
<span class="kw1">class</span> C <span class="br0">{</span>
    <a href="../string/basic_string.html"><span class="kw1233">std::<span class="me2">string</span></span></a> member<span class="sy4">;</span> <span class="co1">// decl-specifier-seq is "std::string"</span>
                        <span class="co1">// declarator is "member"</span>
<span class="br0">}</span> obj, <span class="sy2">*</span>pObj<span class="br0">(</span><span class="sy3">&amp;</span>obj<span class="br0">)</span><span class="sy4">;</span>
<span class="co1">// decl-specifier-seq is "class C { std::string member; }"</span>
<span class="co1">// declarator "obj" defines an object of type C</span>
<span class="co1">// declarator "*pObj(&amp;obj)" declares and initializes a pointer to C</span>
 
<span class="kw4">int</span> a <span class="sy1">=</span> <span class="nu0">1</span>, <span class="sy2">*</span>p <span class="sy1">=</span> nullptr, f<span class="br0">(</span><span class="br0">)</span>, <span class="br0">(</span><span class="sy2">*</span>pf<span class="br0">)</span><span class="br0">(</span><span class="kw4">double</span><span class="br0">)</span><span class="sy4">;</span>
<span class="co1">// decl-specifier-seq is int</span>
<span class="co1">// declarator a = 1 defines and initializes a variable of type int</span>
<span class="co1">// declarator *p = nullptr defines and initializes a variable of type int*</span>
<span class="co1">// declarator (f)() declares (but doesn't define)</span>
<span class="co1">//                  a function taking no arguments and returning int</span>
<span class="co1">// declarator (*pf)(double) defines a pointer to function</span>
<span class="co1">//                  taking double and returning int</span>
 
<span class="kw4">int</span> <span class="br0">(</span><span class="sy2">*</span><span class="br0">(</span><span class="sy2">*</span>foo<span class="br0">)</span><span class="br0">(</span><span class="kw4">double</span><span class="br0">)</span><span class="br0">)</span><span class="br0">[</span><span class="nu0">3</span><span class="br0">]</span> <span class="sy1">=</span> nullptr<span class="sy4">;</span>
<span class="co1">// decl-specifier-seq is int</span>
<span class="co1">// 1. declarator "(*(*foo)(double))[3]" is an array declarator:</span>
<span class="co1">//    the type declared is "/nested declarator/ array of 3 int"</span>
<span class="co1">// 2. the nested declarator is "(*(*foo)(double))", which is a pointer declarator</span>
<span class="co1">//    the type declared is "/nested declarator/ pointer to array of 3 int"</span>
<span class="co1">// 3. the nested declarator is "(*foo)(double)", which is a function declarator</span>
<span class="co1">//    the type declared is "/nested declarator/ function taking double and returning</span>
<span class="co1">//        pointer to array of 3 int"</span>
<span class="co1">// 4. the nested declarator is "(*foo)" which is a (parenthesized, as required by</span>
<span class="co1">//        function declarator syntax) pointer declarator.</span>
<span class="co1">//    the type declared is "/nested declarator/ pointer to function taking double</span>
<span class="co1">//        and returning pointer to array of 3 int"</span>
<span class="co1">// 5. the nested declarator is "foo", which is an identifier.</span>
<span class="co1">// The declaration declares the object foo of type "pointer to function taking double </span>
<span class="co1">//     and returning pointer to array of 3 int"</span>
<span class="co1">// The initializer "= nullptr" provides the initial value of this pointer.</span></pre></div></div>
</div>
<h3><span class="mw-headline" id="Defect_reports">Defect reports</span></h3>
<p>The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
</p>
<table class="dsctable" style="font-size:0.8em">
<tr>
<th> DR
</th>
<th> Applied to
</th>
<th> Behavior as published
</th>
<th> Correct behavior
</th></tr>
<tr>
<td> <a rel="nofollow" class="external text" href="https://cplusplus.github.io/CWG/issues/482.html">CWG 482</a>
</td>
<td> C++98
</td>
<td> the declarators of redeclarations could not be qualified
</td>
<td> qualified declarators allowed
</td></tr>
<tr>
<td> <a rel="nofollow" class="external text" href="https://cplusplus.github.io/CWG/issues/569.html">CWG 569</a>
</td>
<td> C++98
</td>
<td> a single standalone semicolon was not a valid declaration
</td>
<td> it is an empty declaration,<br>which has no effect
</td></tr>
<tr>
<td> <a rel="nofollow" class="external text" href="https://cplusplus.github.io/CWG/issues/1830.html">CWG 1830</a>
</td>
<td> C++98
</td>
<td> repetition of a function specifier in a <span class="t-spar">decl-specifier-seq</span> was allowed
</td>
<td> repetition is forbidden
</td></tr></table>
<h3><span class="mw-headline" id="See_also">See also</span></h3>
<table class="t-dsc-begin">

</table>
<tr><td></td></tr>
</table>

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